Re: [PATCH v2 2/6] drm/panel: Make of_drm_find_panel() return an ERR_PTR() instead of NULL

From: Thierry Reding <thierry.reding@gmail.com>
To: Boris Brezillon <boris.brezillon@bootlin.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
	devicetree@vger.kernel.org, Pawel Moll <pawel.moll@arm.com>,
	Ian Campbell <ijc+devicetree@hellion.org.uk>,
	David Airlie <airlied@linux.ie>,
	dri-devel@lists.freedesktop.org, Rob Herring <robh+dt@kernel.org>,
	Kumar Gala <galak@codeaurora.org>
Subject: Re: [PATCH v2 2/6] drm/panel: Make of_drm_find_panel() return an ERR_PTR() instead of NULL
Date: Fri, 4 May 2018 14:11:40 +0200	[thread overview]
Message-ID: <20180504121140.GR13459@ulmo> (raw)
In-Reply-To: <20180504135820.37b8cea4@bbrezillon>

[-- Attachment #1.1: Type: text/plain, Size: 1746 bytes --]

On Fri, May 04, 2018 at 01:58:20PM +0200, Boris Brezillon wrote:
> On Fri, 4 May 2018 12:18:52 +0200 Thierry Reding <thierry.reding@gmail.com> wrote:
> > On Thu, May 03, 2018 at 06:40:05PM +0200, Boris Brezillon wrote:
[...]
> > >  	return mdp4_lvds_connector->panel ?
> > >  			connector_status_connected :
> > > diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
> > > index 7a03a9489708..fffc80b73966 100644
> > > --- a/drivers/gpu/drm/msm/dsi/dsi_host.c
> > > +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
> > > @@ -1881,7 +1881,7 @@ int msm_dsi_host_register(struct mipi_dsi_host *host, bool check_defer)
> > >  		 * output
> > >  		 */
> > >  		if (check_defer && msm_host->device_node) {
> > > -			if (!of_drm_find_panel(msm_host->device_node))
> > > +			if (IS_ERR(of_drm_find_panel(msm_host->device_node)))
> > >  				if (!of_drm_find_bridge(msm_host->device_node))
> > >  					return -EPROBE_DEFER;
> > >  		}  
> > 
> > Again, pretty weird stuff going on here, prior to the patch. But I think
> > this needs to be changed to take the -ENODEV into account in the next
> > patch. As it is, this will continue to defer probe even if the panel
> > node is disabled.
> 
> Not sure this is a problem. I mean, the code was working before, and we
> had no way to differentiate the -ENODEV vs -EPROBE_DEFER, which in turn
> means that, any driver that assumed that the device would appear at some
> point were just as broken as they are after this patch when the node
> they're pointing to has its status set to "disabled".
> 
> I'm not trying to patch all drivers to take the return code into
> account, just those that might take advantage of it.

Okay, fair enough.

Thierry

[-- Attachment #1.2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]

[-- Attachment #2: Type: text/plain, Size: 160 bytes --]

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel